The biggest obstacle with the Stebel is its bulk. It incorporates a compressor and is rather large. There's no possible way that it would fit in the stock location (the previous FIAMM barely did) but I found a perfect location.
I noticed that the ABS controller bulges out quite far from the frame on the right side of the bike. The space on the opposite side of the frame is vacant and the fairings are symmetrical so it stood to reason that there would be room in that location. Hell there was even a threaded hole on the frame to use as a mounting point and a chassis ground nearby to make wiring easier. After this photo was taken I reinstalled the top fairing / headlight so I could make sure I had clearance where I needed it.
As you can see, the Nautilus is substantially larger than the previous Fiamm and immensely larger than the stock "meep meep" horn.
A device like the Nautilus draws substantially more current than the stock horn, and therefore has the potential to fry the light duty horn switch. The solution is to wire it through a relay. Basically a relay is a heavy-duty switch which is contolled by a light-duty switch. This also allows the new horn a direct connection to the battery so it can blast away to its maximum effect. I'm not very skilled electrically... this would be my first encounter with a relay and I learned all this as I went. I used the aid of a handy online tutorial. I wanted a clean installation so I bought some quality automotive connectors and a fuse holder.
I used the soft metal bracket from the Fiamm, test-fitting it and bending it into a "Z" shape that would keep the Nautilus tidy against the frame.
Here is the Bosch relay that came with the Nautilus. All hooked up. The heavy white wire is my power wire. I used some heavy-duty speaker wire from an old kit I had. Comically, this wire was labeled "subwoofer".
I drilled a little hole in the inner cowl where I would mount the relay next to the upper harness connector.
I secured it with that old favourite fastener of mine... a windshield screw. (I have a package of them) It is the perfect size and provides a "shock mount".
Here is the red relay secured in place.
And here is the Nautilus bolted in tight against the frame in the desirable downward-facing position. This is exactly where the bulky ABS controller mounts on the opposite side of the bike. I test-fitted the left fairing panel to make sure it fit.
Here is the fuse holder and the power wire running up to the relay:
I briefly tested the horn inside the garage... big mistake. I gave myself a splitting headache. It's FUCKING LOUD!!!
I wheeled it outside to test it properly and piss off my neighbours. Turn your speakers all the way up and press your ear firmly up against one of them to fully appreciate the experience: